Ballast water is essential for the safe operation of ships. It is used to adjust the overall weight of the vessel and its internal distribution in order to keep the ship floating safely, upright and in a stable condition. It is used to compensate for different cargo loads that a ship may carry at different times, including during loading and unloading. It also provides stability and manoeuvrability during transit.
Ballast is defined as any solid or liquid that is brought on board a ship to increase stability. Ballasting is essential if a ship is carrying a heavy load in one hold and a lighter load in another, or when the ship is empty or if it faces rough seas.
Prior to the 1880s, ships used solid ballast materials such as rocks and sand, which had to be manually shoveled into cargo holds, and similarly discharged when cargo was to be loaded on board. Unfortunately, if not properly secured, solid ballast is prone to shifting in heavy seas causing instability. With the introduction of steel-hulled ships and pumping technology, water became the ballast of choice.
Water can be easily pumped in and out of ballast tanks and requires little manpower. When ships need ballast, water is pumped from the sea where the ship is located into the ships’ ballast water tanks, which adds weight to key parts of the ship. Ballast water is discharged at sea when it is no longer needed or when the weight of the ship needs to be lightened.
Today, ocean going vessels have ballast tanks incorporated into their design. The number and size of ballast tanks varies according to a ship’s type and design. Most ships are equipped with a range of ballast capabilities and capacities, but generally ballast equates to 25-30% of a ship’s dead weight tonnage.
Why is ballast water an issue?
The process of loading and unloading untreated ballast water poses a major threat to the environment, public health and the economy as ships become a vector for the transfer of organisms between ecosystems, from one part of the world to another.
When ballast water is pumped into a ship many microscopic organisms and sediments can be introduced into a ship’s ballast tanks. These organisms include bacteria, microbes, small invertebrates, eggs, cysts and larvae of various species. Many of these organisms are able to survive in a ship’s ballast tanks. When the ballast water is discharged, the organisms are released into new environments. If suitable conditions exist in the new environment into which they are released, these species can survive, reproduce and become aquatic invasive species.
- 10 billion tonnes of ballast water is transported worldwide every year, which could fill ~4 million olympic sized swimming pools
- 7,000 species are transferred in ballast water every hour of everyday
- There is 1 new invasion every 9 weeks
The green crab, zebra mussel, and round goby are all examples of aquatic invasive species which can be found in Canadian waters. More information about these species and other aquatic invasive species enabled by ballast water can be found here.
What is being done in Canada to mitigate the impacts of ballast water?
Transport Canada has implemented regulations in order to prevent ecological and environmental problems resulting from the discharge of ballast water.
- Under the Canada Shipping Act, the Ballast Water Control and Management Regulations were created to address the growing problem of non-native aquatic species being discharged in ships’ ballast water
More information on Canada’s Ballast Water Control and Management Regulations can be found here.
Additionally, Canada is a Member State to the International Maritime Organization (IMO), a specialized agency of the United Nations responsible for measures to improve the safety and security of international shipping and to prevent pollution from ships.
- In 2004, the IMO adopted The International Convention for the Control and Management of Ships’ Ballast Water and Sediments
The Convention aims to prevent the spread of harmful aquatic organisms from one region to another, by establishing standards and procedures for the management and control of ships’ ballast water and sediments. Canada ratified to the Ballast Water Management Convention on April 8th 2010.
What you need to know about the Ballast Water Management Convention:
The Ballast Water Management Convention enters into force September 8th 2017, 12 months after the ratification of a minimum of 30 states, representing 35% of world shipping tonnage.
In a landmark step towards halting the spread of invasive aquatic species, the Convention will require all ships to implement a ballast water and sediments management plan which must include:
- A ballast water management system which adheres to the guidelines set out by the IMO. This might include:
- filtration systems
- chemical disinfection
- ultra-violet treatment
- deoxygenation treatment
- thermal treatment (heat)
- cavitation treatment (acoustic)
- electric pulse systems
- magnetic field treatment
- Duties of the personnel on board for carrying out ballast operations
- The operational procedure along with the method to be used for ballasting
- The locations where ballast water exchange is to be conducted
- The international rules and regulations for different port state controls all over the world
- The locations of ports providing shore discharge facilities of sediments and ballast water
- A ballast water exchange record book is to be kept and the following data is to be noted:
- The date of the operation
- The ship’s ballast tank used in the operation.
- The temperature of the ballast water.
- The salinity of the ballast water in PPM (salt content in parts per million).
- The position of the ship (latitude and longitude).
- The amount of ballast water involved in operation.
- The date and identification of the tank last cleaned.
- If there is accidental discharge of ballast exchange it must be entered and signed. Same information is to be given to concerned port state authority.
Ships constructed after September 8th 2017, must comply upon delivery, while existing ships must comply by their first International Oil Pollution Prevention (IOPP) certificate renewal after September 8th 2019. This will result in all ships belonging to nations having ratified the Convention, having a ballast water management plan in place by 2024.
“This is a truly significant milestone for the health of our planet. The spread of invasive species has been recognized as one of the greatest threats to the ecological and the economic well-being of the planet. These species are causing enormous damage to biodiversity and the valuable natural riches of the earth upon which we depend. Invasive species also cause direct and indirect health effects and the damage to the environment is often irreversible. The entry into force of the Ballast Water Management Convention will not only minimize the risk of invasions by alien species via ballast water, it will also provide a global level playing field for international shipping, providing clear and robust standards for the management of ballast water on ships.”
Kitach Lim, Secretary General of the International Maritime Organization
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Published September 7, 2017
Last modified on July 25, 2018